Wireless Monitoring of Pump Jack Sucker Rod Loading and Position

ABSTRACT

Forces on and respective positions of a pump jack sucker rod are determined in real time by load cells attached to the sucker rod and a position sensor, and are stored for further processing. A wireless transmitter transmits stored load and position values, calculated process parameters, and/or exception alerts to a wireless spread spectrum receiver that can be coupled to a motor speed controller used to set the rotational speed of the pump jack motor, and/or to monitoring systems, such as a central controller used to optimize total field production.

RELATED PATENT APPLICATION

This application claims priority to commonly owned U.S. ProvisionalPatent Application Ser. No. 61/165,628; filed Apr. 1, 2009; entitled“Wireless Monitoring Of Pump Jack Sucker Rod Loading And Position,” byRick A. Lawson and Doneil Dorado; and is hereby incorporated byreference herein for all purposes.

TECHNICAL FIELD

The present disclosure relates to oil well pump jacks and, moreparticularly, to monitoring and control of the pump jacks to optimizepumping operation of the pump jacks in producing production from the oilwells.

BACKGROUND

Historically, oil wells which must produce by artificial lift have usedhorsehead-type pumping units such as those made by Lufkin Industries andothers. To counterbalance the weight of the sucker rod string,counterweights are used, either mounted on the walking beam or arotary-type mounted on the gear box Pittman arm. Another class ofpumping unit (also made by Lufkin) uses an air cylinder in place of themetal counterweights. The effect is roughly the same. The sucker rodstring reciprocates up and down in a sine wave motion caused by rotationof the Pittman arm by an electric motor.

The electric motor drives the pumping jack sucker rod string on as tolift oil in discreet slugs or pulses from a pocket at the bottom of thewell bore to the surface. Such a pumping system typically comprises apower driven jack or beam which reciprocates on a pivot to reciprocate astring of well (sucker) rod up and down in the well casing, and therebyprovide a lifting or pumping action that delivers the crude oil andbrine from the well pocket to the well head at the surface andthereafter storage.

The rate at which the crude oil in an oil well migrates to the well boreand fills the well pocket may vary widely from one well to anotherdepending upon specific geologic conditions in the oil bearing sands,and the age of the oil field in terms of the proportion of recoverablecrude oil which has been removed from the geologic formations. In maturewells, commonly known as stripper wells, the maximum attainableproduction rate will depend entirely on how quickly the spontaneousmigration of crude oil to the well pocket can fill the pocket.Typically, in such wells the pumping capacity of the pumping jack is fargreater than the capacity of the field to refill well pocket with crudeoil from the oil bearing formations. Even in newer, more productivewells the pumping capacity of the pumping jack may far exceedspontaneous well pocket refill rates.

To accommodate these well pocket refill rates and other limitations ofoil well production, the rotational speed of the electric motor iscontrolled so as to optimize fluid pumping action by the well sucker rodstring of the pumping jack, so that pumping action is not too fast ortoo slow.

A pump motor speed controller is used to control the pumping action ofthe pump jack from various parameters of the pump jack. For example, thewell sucker rod string load (up and down) and rotational speed of thepump motor may be used in determining optimal pumping action, and/or toalert for undesirable conditions in the well.

FIG. 1 illustrates a schematic elevational diagram of a prior technologypump jack system having hardwired sucker rod load and position sensors,and connected to a well sucker rod string. The pump jack system,represented by the numeral 100, comprises a sucker rod string 110, apolish rod 120, a horsehead 122, a rocker beam 124, connecting rod 132,counter weight 134, Pittman arm 136, motor/gear drive 138, frame 128 andbase 146. As the motor/gear drive 138 rotates, the Pittman arm 136causes the connecting rod 132 to push up or pull down one end of therocker beam 124. On the other end of the rocker beam 124 is thehorsehead 122 connected to the polish rod 120. As the horsehead 122moves up and down so does the polish rod 120 which in turn moves thesucker rod string 110 in and out of the well bore pipe 118. The wellbore pipe 118 is terminated at flange/fluid takeoff assembly 116 that isadapted to allow fluid (or gas) being pumped out of the well bore pipe118 to flow to a storage tank/pipeline (not shown). The flange/fluidtakeoff assembly 116 also is used to seal around a portion of the suckerrod string 110 so that well fluid does not spill onto the ground.

Axial forces on the sucker rod string 110 may be measured by a load cell114 that determines the axial forces applied to the sucker rod string110 when being draw upwards and when being pushed downward. The loadcell 114 accomplishes these measurements by being held in a fixedposition on the sucker rod string 110 between a top clamp collar 112 aand a bottom clamp collar 112 b.

The vertical position of the sucker rod string 110 relative to the downhole well pocket may be determined by positional information from arotation position sensor 140, e.g., Hall effect device, that indicatesthe rotational position of the Pittman arm 136. The vertical position ofthe sucker rod string 110 may then be correlated with the rotationalposition of the Pittman arm 136. Once the sucker rod string 110 axialforces and associated vertical positions are available, a determinationcan be made for a desired rotational speed(s) of the motor/gear drive138 to optimize well fluid pumping action. Note that the rotationalspeed can be varied during a pumping cycle (360 degree rotation of thePittman arm 136) to further optimize the well fluid pumping action.

The load cell 114 may be electrically coupled to a motor speedcontroller 144 through a flexible electrical cable 126 that may beattached to the frame 128 with a junction/strain relief box 130. Therotation position sensor 140 may be electrically coupled to the motorspeed controller 144 through an electrical conduit or cable 142. Theelectrical cable 126 may be routed over the horsehead 122 and across therocker beam 124.

Flexibility of the electrical cable 126 is very important in that theload cell 114 is constantly moving up and down. However this constantflexing of the electrical cable 126 causes failures thereto thatrequires maintenance and replacement in the field. Also the rotationposition sensor 140 is subject to failure and also requires periodicmaintenance and/or replacement. Working in close proximity to thePittman arm 136 when servicing the rotation position sensor 140 posesserious safety issues and careless field service technicians have beeninjured, some severely, by coming in contact with a Pittman arm 136 thataccidentally starts to rotate while service/replacement of the positionsensor 140 is being performed. Thus, service, reliability and safetyproblems exist in present technology load and position measurementinstallations and servicing of pump jack systems, specifically forfatigue of the connecting electrical cables and the hazards ofaccidental rotation of machinery while servicing sensors in closeproximity thereto.

SUMMARY

Therefore a need exists to overcome the above-identified problems aswell as other shortcomings and deficiencies of existing technologies byproviding wireless transmission of data from sucker rod load andposition sensors, and then using that data to control the pump jacksystem operating parameters so as to optimize fluid lift from the wellpocket.

According to the teachings of this disclosure, a wireless sensor packageis mechanically and electrically attached to the load cell 114, andmoves therewith. The wireless sensor package comprises an electricalinterface for receiving electrical signals from the load cell 114, and aposition sensor, e.g., a tri-axial accelerometer, or device formeasuring distance from a fixed point, e.g., ultrasonic, radiofrequency, infrared, laser light, etc. In addition, a downholetemperature gradient may be determined by measurement of the elongationof the well bore pipe 118 projecting out of the ground (e.g., distancefrom ground level to the top of the well bore pipe 118). Well pressureand flow rate may also be measured at the flange/fluid takeoff assembly116.

The wireless sensor package is adapted to transmit the sucker rod loadand position information over a radio frequency channel(s), e.g.,short-range radio, for example but not limited to, frequencies at about315 MHz, 433 MHz, 868 MHz, 902 to 928 MHZ, 2.4 to 2.5 GHz, 5.7 to 5.8GHz, etc. In addition, any form of transmission and modulationtechniques may be used, for example but not limited to, spread spectrumto a compatible receive, e.g., spread spectrum receiver, coupled to amotor speed controller. Computations for optimal motor speeds from thewireless load and position data may be performed in the wireless sensorpackage and/or the wireless motor speed controller. A central controllerreceiving load and position information and/or motor speeds from each ofthe plurality of pump jacks may further be used to control pump speedsof the plurality of jump jacks so as to optimize oil field production,e.g., flow rates of pumped product. The central controller may alsodetermine optimal pumping parameters of each of the plurality of pumpjacks so as to maximize oil field production.

According to a specific example embodiment of this disclosure, a pumpjack adapted for monitoring sucker rod load and position comprises: asucker rod string in a well bore pipe; a polished rod coupled to thesucker rod string; a horsehead coupled to the polished rod; a rockerbeam coupled to the horsehead; a connecting rod coupled to the rockerbeam; a counter weight coupled to the connecting rod; a pittman armcoupled to the connecting rod and counter weight; a variable speedmotor-gear drive assembly coupled to the pittman arm for rotationalmovement thereof; a frame pivotally coupled to the rocker beam; a baseattached to the frame; first and second force sensors attached to aproximate end of the sucker rod string, wherein the first and secondforce sensors measure elongation and compression stresses, respectively,of the sucker rod string while the sucker rod string moves up and downin the well bore pipe; a position sensor attached toward the proximateend of the sucker rod string, wherein the position sensor determinespositions of the sucker rod string; a sensor interface assembly havingwireless transmitting capabilities, wherein the sensor interfaceassembly is attached to the sucker rod string, and is coupled to thefirst and second force measurement sensors and the position sensor,whereby the sucker rod string forces and position information arewirelessly transmitted therefrom; and a wireless receiver coupled to thevariable speed motor-gear drive assembly, wherein the wireless receiverreceives the force and position information transmitted from theinterface assembly for determining control of rotational speed of thevariable speed motor-gear drive assembly.

According to another specific example embodiment of this disclosure, anapparatus for monitoring position and load of a sucker rod in a pumpjack, comprises: first and second force sensors attached at a proximateend of a sucker rod string of a pump jack, wherein the first and secondforce sensors measure elongation and compression stresses, respectively,of the sucker rod string while the sucker rod string moves up and downin a well bore pipe; a position sensor attached toward the proximate endthe sucker rod string, wherein the position sensor determines positionsof the sucker rod string; and a sensor interface assembly havingwireless transmitting capabilities, wherein the sensor interfaceassembly is attached to the sucker rod string, and is coupled to thefirst and second force measurement sensors and the position sensor,whereby the sucker rod string forces and position information arewirelessly transmitted therefrom.

According to still another specific example embodiment of thisdisclosure, a pump jack adapted for monitoring sucker rod load andposition comprises: a sucker rod string in a well bore pipe; a polishedrod coupled to the sucker rod string; a horsehead coupled to thepolished rod; a rocker beam coupled to the horsehead; a connecting rodcoupled to the rocker beam; a counter weight coupled to the connectingrod; a pittman arm coupled to the connecting rod and counter weight; avariable speed motor-gear drive assembly coupled to the pittman arm forrotational movement thereof; a frame pivotally coupled to the rockerbeam; abuse attached to the frame; first and second force sensorsattached to a proximate end of the sucker rod string, wherein the firstand second force sensors measure elongation and compression stresses,respectively, of the sucker rod string while the sucker rod string movesup and down in the well bore pipe; a sensor interface assembly havingwireless transmitting capabilities, wherein the sensor interfaceassembly is attached to the sucker rod string, and is coupled to thefirst and second force measurement sensors, whereby the sucker rodstring force information is wirelessly transmitted therefrom; a distancemeasuring device attached on a plan of the base and under the sensorinterface assembly, wherein the position sensor determines positions ofthe sucker rod string by measuring distances between the distancemeasuring device and the sensor interface assembly; and a wirelessreceiver coupled to the variable speed motor-gear drive assembly,wherein the wireless receiver receives the force information transmittedfrom the sensor interface assembly, and wherein position informationfrom the distance measuring device is coupled to the variable speedmotor-gear drive assembly, whereby control of rotational speed of thevariable speed motor-gear drive assembly is determined from the forceand position information.

According to yet another specific example embodiment of this disclosure,an apparatus for monitoring position and load of a sucker rod in a pumpjack comprises: first and second force sensors attached at a proximateend of a sucker rod string of a pump jack, wherein the first and secondforce sensors measure elongation and compression stresses, respectively,of the sucker rod string while the sucker rod string moves up and downin a well bore pipe; a sensor interface assembly having wirelesstransmitting capabilities, wherein the sensor interface assembly isattached to the sucker rod string, and is coupled to the first andsecond force measurement sensors, whereby the sucker rod string forceinformation is wirelessly transmitted therefrom; a distance measuringdevice attached on a plane of a base of the pump jack and under thesensor interface assembly, wherein the distance measuring devicedetermines positions of the sucker rod string by measuring distancesbetween the distance measuring device and the sensor interface assembly;and a wireless receiver coupled to the variable speed motor-gear driveassembly, wherein the wireless receiver receives the force informationtransmitted from the sensor interface assembly, and wherein positioninformation from the distance measuring device is coupled to thevariable speed motor-gear drive assembly, whereby control of rotationalspeed of the variable speed motor-gear drive assembly is determined fromthe force and position information.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present disclosure thereof may beacquired by referring to the following description taken in conjunctionwith the accompanying drawings wherein:

FIG. 1 illustrates a schematic elevational diagram of a prior technologypump jack system having hardwired sucker rod load and position sensors,and connected to a well sucker rod string;

FIG. 2 illustrates a schematic elevational diagram of a pump jack systemhaving wireless sucker rod load and position sensors coupled to a wellsucker rod string, a distance measuring device for determining well borepipe elongation, and a wireless data input motor speed controller,according to a specific example embodiment of this disclosure;

FIG. 3 illustrates a more detailed schematic block diagram of thewireless sensor packages shown in FIG. 2;

FIG. 4 illustrates a schematic elevational diagram of a pump jack systemhaving wireless sucker rod load and distance measurement sensors coupledto a well sucker rod string, a distance measuring device for determiningwell bore pipe elongation, and a wireless data input motor speedcontroller, according to another specific example embodiment of thisdisclosure;

FIG. 5 illustrates a more detailed schematic block diagram of thewireless sensor packages shown in FIG. 4;

FIG. 6 illustrates a schematic elevational diagram of a pump jack systemhaving wireless sucker rod load measurement sensors coupled to a wellsucker rod string, distance measuring devices for determining wellsucker rod string positions and well bore pipe elongation, and awireless data input motor speed controller, according to still anotherspecific example embodiment of this disclosure;

FIG. 7 illustrates a more detailed schematic block diagram of thewireless sensor packages shown in FIG. 6; and

FIG. 8 illustrates schematic diagrams of various power sources availablefor powering the wireless sensor packages shown in FIGS. 3, 5 and 7,according to specific example embodiments of this disclosure.

While the present disclosure is susceptible to various modifications andalternative forms, specific example embodiments thereof have been shownin the drawings and are herein described in detail. It should beunderstood, however, that the description herein of specific exampleembodiments is not intended to limit the disclosure to the particularforms disclosed herein, but on the contrary, this disclosure is to coverall modifications and equivalents as defined by the appended claims.

DETAILED DESCRIPTION

Referring now to the drawing, the details of specific exampleembodiments are schematically illustrated. Like elements in the drawingswill be represented by like numbers, and similar elements will berepresented by like numbers with a different lower case letter suffix.

Referring to FIG. 2, depicted is a schematic elevational diagram of apump jack system having wireless sucker rod load and position sensorscoupled to a well sucker rod string, a distance measuring device fordetermining well bore pipe elongation, and a wireless motor speedcontroller, according to a specific example embodiment of thisdisclosure. The pump jack system, according to the teachings of thisdisclosure and generally represented by the numeral 200, comprises asucker rod string 110, a polish rod 120, a horsehead 122, a rocker beam124, connecting rod 132, counter weight 134. Pittman arm 136, motor/geardrive 138, frame 128 and base 146. A wireless sensor package 250 ismechanically and electrically attached to the load cell 114, and movestherewith. In addition, another wireless sensor package 254 attached atabout the top of the well bore pipe 118, e.g., coupled to theflange/fluid takeoff assembly 116. The wireless sensor package 254comprises a distance measurement device that accurately measures adistance, d, from the wireless sensor package 254 to a reference point256, e.g., a target at ground level.

As the motor/gear drive 138 rotates, the Pittman arm 136 causes theconnecting rod 132 to push up or pull down one end of the rocker beam124. On the other end of the rocker beam 124 is the horsehead 122connected to the polish rod 120. As the horsehead 122 moves up and downso does the polish rod 120 which in turn moves the sucker rod string 110in and out of the well bore pipe 118. The well bore pipe 118 isterminated at the flange/fluid takeoff assembly 116 that is adapted toallow fluid (or gas) being pumped out of the well bore pipe 118 to flowto a storage tank/pipeline (not shown). The flange/fluid takeoffassembly 116 also is used to seal around a portion of the sucker rodstring 110 so that well fluid does not spill onto the ground. Pressureand flow rate sensors may also be incorporated into the wireless sensorpackage 254. It is contemplated and within the scope of this disclosurethat the sensor package 254 may alternatively be hard wired to the motorspeed controller 258 since the sensor package 254 is stationary withrespect to the well bore pipe 118.

Axial forces on the sucker rod string 110 may be measured by a load cell114 that determines the axial forces applied to the sucker rod string110 when being draw upwards and when being pushed downward. The loadcell 114 accomplishes these measurements by being held in a fixedposition on the sucker rod string 110 between a top clamp collar 112 aand a bottom clamp collar 112 b. The load cell 114 may be, for examplebut is not limited to, a Lufkin Industries model 1923.

The wireless sensor package 250 is mechanically and electrically coupledto the load cell 114, and moves therewith. A right angle coupling 252may be used for mounting thereof. The wireless sensor package 250comprises an electrical interface for receiving electrical signals fromthe load cell 114, and a position sensor, e.g., a tri-axialaccelerometer (see FIG. 3). The wireless sensor package 250 is adaptedto transmit the sucker rod load and position information over a radiofrequency channel(s), e.g., short-range radio, for example but notlimited to, frequencies at about 315 MHz, 433 MHz, 868 MHz, 902 to 928MHZ, 2.4 to 2.5 GHz, 5.7 to 5.8 GHz, etc. In addition, any form oftransmission and modulation techniques may be used, for example but notlimited to, spread spectrum to a compatible receive, e.g., spreadspectrum receiver, coupled to a motor speed controller 258. Computationsfor optimal motor speeds from the wireless load and position data may beperformed in the wireless sensor package 250 and/or the wireless motorspeed controller 258. A central controller receiving load and positioninformation and/or motor speeds from each of the plurality of pump jacksmay further be used to control pump speeds of the plurality of jumpjacks so as to optimize oil field production, e.g., flow rates of pumpedproduct. The central controller (not shown) may also determine optimalpumping parameters of each of the plurality of pump jacks so as tomaximize oil field production.

Once the sucker rod string 110 axial forces and associated verticalpositions thereof are available, a determination(s) can be made for adesired rotational speed(s) of the motor/gear drive 138 to optimize wellfluid pumping action. Note that the rotational speed can be variedduring a pumping cycle (360 degree rotation of the Pittman arm 136) tofurther optimize the well fluid pumping action.

Referring to FIG. 3, depicted is a more detailed schematic block diagramof the wireless sensor packages shown in FIG. 2. The wireless sensorpackage 250 may comprise a position sensor 360, a position sensorinterface 362, top and bottom load cell interfaces 364, data processinglogic and memory storage 368, a wireless transmitter 370 a, and a powersource 366. The position sensor 360 may be a tri-axial accelerometer,for example but not limited to, Analog Devices ADXL330.

As the sucker rod string 110 moves up and down, representedschematically by the heavy line double arrow, the position sensor 360determines at the movement distances from a reference point. Thus realtime position signals representative of the positions of the sucker rodstring 110 are available from the position sensor 360. The power source366 supplies power to the position sensor 360, the data processing logicand memory storage 368, and the wireless transmitter 370. The interfaces362 and 364 may receive power from the data processing logic and memorystorage 368, and the load cells 114 may receive power from theirrespective interfaces 364.

The top and bottom load cells 114 a and 114 b also make available realtime signals representative of the up and down forces, respectively,being applied to the sucker rod string 110. These real time position andforce signals are transferred by the respective position sensorinterface 362 and load cell interfaces 364 to the data processing logicand memory storage 368. The data processing logic and memory storage 368may comprise a digital processor (not shown) and a memory (not shown).The data processing logic and memory storage 368 may be used forprocessing the real time position and force signals into optimal motorspeed control values to be transmitted to the wireless motor speedcontroller 258 through the wireless transmitter 370. Also values of thereal time position and force signals may be stored in the memory of thedata processing logic and memory storage 368 for historical andexception reporting, e.g., real time position and/or force values thatare outside of the expected norm, and may be exception reported throughthe wireless transmitter 370 to a control and monitoring system (notshown) or as a shutdown and/or alarm signal to the wireless motor speedcontroller 258.

The sensor package 254 may comprise a distance detector 372, e.g., adistance determining device using, for example but not limited to,ultrasonic, radio frequency (radar), infrared or laser light timed pulsetransmissions. Another wireless transmitter 370 b may be used totransmit the distance information from the distance detector 372 andused for determining the elongation of the well bore pipe 118 due to anincrease of the downhole temperature. In addition, pressure and/or flowrate sensors may be coupled at the flange/fluid takeoff assembly 116.The sensor package 254 may be powered through an internal power source(e.g., wireless sensor package) or from the motor speed controller 258(hardwired).

Referring to FIG. 4, depicted is a schematic elevational diagram of apump jack system having wireless sucker rod load and distancemeasurement sensors coupled to a well sucker rod string, a distancemeasuring device for determining well bore pipe elongation, and awireless motor, speed controller, according to another specific exampleembodiment of this disclosure. The pump jack system, according to theteachings of this disclosure and generally represented by the numeral400, comprises a sucker rod string 110, a polish rod 120, a horsehead122, a rocker beam 124, connecting rod 132, counter weight 134, Pittmanarm 136, motor/gear drive 138, frame 128 and base 146. A wireless sensorpackage 450 is mechanically and electrically coupled to the load cell114, and moves therewith. In addition, another wireless sensor package254 may be attached at about the top of the well bore pipe 118, e.g.,coupled to the flange/fluid takeoff assembly 116. The sensor package 254comprises a distance measurement device that accurately measures adistance, d₁, from the sensor package 254 to a reference point 256 a,e.g., a target at ground level. The sensor package 254 may be wirelessor hard wired to the motor speed controller 258.

Axial forces on the sucker rod string 110 may be measured by the loadcell 114 as more fully described hereinabove. The wireless sensorpackage 450 comprises an electrical interface for receiving electricalsignals from the load cell 114, and a distance measurement sensor, e.g.,ultrasonic, radio frequency, infrared, laser light that measure adistance, d₂, representing the vertical distance of the load cell 114from the reference point 256 b, e.g., a target at ground level. Thewireless sensor package 450 is adapted to transmit the sucker rod loadand distance information over a radio frequency channel(s) as describedmore fully hereinabove.

It is contemplated and within the scope of this disclosure that thedistance measurement device that measures the distance (position) of theload cell 114 may be located at the reference point 256 b at or aboutground level. By locating this distance measurement device at a fixedlocation (reference point 256 b) it can now be either wireless or wiredto the motor controller 258. In addition, the movable wireless sensorpackage 450 may be simplied as it need only transmit load cell 114information wirelessly, as more fully described herein. Also anyintellegent electronics may now be located with the stationary (fixed)distance measurement device, and a very low power and simple (e.g.,Bluetooth) wireless communications protocol may be utilized for the realtime load cell data.

Referring to FIG. 5, depicted is a more detailed schematic block diagramof the wireless sensor packages shown in FIG. 4. The wireless sensorpackage 450 may comprise a distance detector 560, a distance detectorinterface 562, top and bottom load cell interfaces 364, data processinglogic and memory storage 368, a wireless transmitter 370 a, and a powersource 366. The distance detector 560 may be similar to the distancedetector 372 as more fully described hereinabove.

As the sucker rod string 110 moves up and down, representedschematically by the heavy line double arrow, the distance detector 560determines the distances, d₂, from the reference point 256 b. Thus realtime positions derived from the measured distances, d₂, arerepresentative of the positions of the sucker rod string 110. The powersource 366 supplies power to the distance detector 560, the dataprocessing logic and memory storage 368, and the wireless transmitter370 a. The interfaces 362 and 364 may receive power from the dataprocessing logic and memory storage 368, and the load cells 114 mayreceive power from their respective interfaces 364.

The top and bottom load cells 114 a and 114 b also make available realtime signals representative of the up and down forces, respectively,being applied to the sucker rod string 110. These real time position andforce signals are transferred by the respective distance detectorinterface 562 and load cell interfaces 364 to the data processing logicand memory storage 368. The data processing logic and memory storage 368may comprise a digital processor (no(shown) and a memory (not shown).The data processing logic and memory storage 368 may be used forprocessing the real time position and force signals into optimal motorspeed control values to be transmitted to the wireless motor speedcontroller 258 through the wireless transmitter 370 a. Also values ofthe real time position and force signals may be stored in the memory ofthe data processing logic and memory storage 368 for historical andexception reporting, e.g., real time position and/or force values thatare outside of the expected norm, and may be exception reported throughthe wireless transmitter 370 a to a control and monitoring system (notshown) or as a shutdown and/or alarm signal to the wireless motor speedcontroller 258.

It is contemplated and within the scope of this disclosure that thedistance detector 560, the distance detector interface 562 and the dataprocessing and storage 368 may be located at the fixed location(reference point 256 b) and the wireless sensor package 450 need onlycomprise the load cell interfaces 364, a power source 366 a and awireless transmitter 370 a. The housing of the wireless sensor package450 could serve as a reflective target for the distance detector 560 ora distance measuring signal reflective plate can be attached thereto.See also FIG. 7 and the disclosure therefor hereinbelow.

The sensor package 254 may comprise a distance detector 372, e.g., adistance determining device using, for example but is not limited to,ultrasonic, radio frequency (radar), infrared or laser light timed pulsetransmissions. Another wireless transmitter 370 b may be used totransmit the distance information from the distance detector 372 andused for determining the elongation of the well bore pipe 118 due to anincrease of the downhole temperature. In addition, pressure and/or flowrate sensors may be coupled at the flange/fluid takeoff assembly 116.

Referring to FIG. 6, depicted is a schematic elevational diagram of apump jack system having wireless sucker rod load measurement sensorscoupled to a well sucker rod string, distance measuring devices fordetermining well sucker rod string positions and well bore pipeelongation, and a wireless motor speed controller, according to stillanother specific example embodiment of this disclosure. The pump jacksystem, according to the teachings of this disclosure and generallyrepresented by the numeral 600, comprises a sucker rod string 110, apolish rod 120, a horsehead 122, a rocker beam 124, connecting rod 132,counter weight 134, Pittman arm 136, motor/gear drive 138, frame 128 andbase 146. A wireless sensor package 650 is mechanically and electricallyattached to the load cell 114, and moves therewith. In addition, anotherwireless sensor package 654 attached at about the top of the well borepipe 118, e.g., coupled to the flange/fluid takeoff assembly 116. Thesensor package 654 comprises distance measurement devices thataccurately measure distance, d_(b), from the sensor package 654 to areference point 256, e.g., a target at ground level, and distance,d_(a), from the sensor package 654 to the sensor package 650 (also usedas a target). The sensor package 654 may be wireless or hard wired tothe motor speed controller 258 since it remains stationary. The sum ofthe measured distances, d_(a) and d_(b), plus the height of the sensorpackage 654 will be representative of an accurate measured distance ofthe load cell 114 from the reference point 256. Both distances, d_(a)and d_(b), have to be taken into account since elongation of the wellbore pipe 118 vary depending upon the temperatures along the pipe 118.An alternative mounting of a distance measurement sensor (not shown) atthe fixed reference point 256 may be used and then the distance from theground mounted (or fixed pedistile mounted) distance detector in thesensor package 654 a would measure the housing as a target of the sensorpackage 650. An advantage of putting the distance measurement detectorsin the fixed sensor package 652 is that only the load cell sensors inthe sensor package 650 need be wireless, though preferably all sensorpackages 650 and 652 may be wireless.

Axial forces on the sucker rod string 110 may be measured by the loadcell 114 as more fully described hereinabove. The wireless sensorpackage 650 comprises an electrical interface for receiving electricalsignals from the load cell 114. The wireless sensor package 650 isadapted to transmit the sucker rod load over a radio frequencychannel(s) as described more fully hereinabove.

Referring to FIG. 7, depicted is a more detailed schematic block diagramof the wireless sensor packages shown in FIG. 6. The wireless sensorpackage 650 may comprise top and bottom load cell interfaces 364, dataprocessing logic and memory storage 368, a wireless transmitter 370 a,and a power source 366. It is contemplated and within the scope of thisdisclosure that the data processing and storage 368 may be located inthe sensor package 652 and that the wireless transmitter 370 a maycommunicate directly with a receiver (not shown) in the sensor package652. This will further reduce the power consumption used by the sensorpackage 650. The distance detector 760 may be similar to the distancedetector 560 as more fully described hereinabove.

As the sucker rod string 110 moves up and down, representedschematically by the heavy line double arrow, the distance detector 760determines the distance, d_(a), from the top of the sensor package 654housing, and the distance detector 762 determines the distance, d_(b),from the top of the well bore pipe 118 to the reference point 256 (e.g.,ground reference). Thus real time positions derived from the measureddistances, d_(a) plus d_(b) plus the height of the sensor package 654housing, represent the positions of the sucker rod string 110. Powersources supply power to the distance detectors 760 and 762, the dataprocessing logic and memory storage 368, and the wireless transmitters370. The interfaces 362 and 364 may receive power from the dataprocessing logic and memory storage 368, and the load cells 114 mayreceive power from their respective interfaces 364. The data processinglogic may also be located in the sensor package 654 and that the sensorpackage 654 may be either wireless or hard wired to the motor controller258. Also the wireless transmitter 370 a may send the load cellinformation first to a receiver (not shown) in the stationary sensorpackage 654 where all of the smart processing may also be located.

The top and bottom load cells 114 a and 114 b also make available realtime signals representative of the up and down forces, respectively,being applied to the sucker rod string 110. These real time position andforce signals are transferred by the respective distance detectorinterface 562 and load cell interfaces 364 to the data processing logicand memory storage 368. The data processing logic and memory storage 368may comprise a digital processor (not shown) and a memory (not shown).The data processing logic and memory storage 368 may be used forprocessing the real time position and force signals into optimal motorspeed control values to be transmitted to the wireless motor speedcontroller 258 through the wireless transmitter 370 a. Also values ofthe real time position and force signals may be stored in the memory ofthe data processing logic and memory storage 368 for historical andexception reporting, e.g., real time position and/or force values thatare outside of the expected norm, and may be exception reported throughthe wireless transmitter 370 a to a control and monitoring system (notshown) or as a shutdown and/or alarm signal to the wireless motor speedcontroller 258.

Referring to FIG. 8, depicted are schematic diagrams of various powersources available for powering the wireless sensor packages shown inFIGS. 3, 5 and 7, according to specific example embodiments of thisdisclosure. A rechargeable battery 366 a may be used as the power source366. A capacitor 366 b may be charged as described hereinafter and usedas the power source 366. A battery and solar cell charger 366 c may beused as the power source 366. An inductive pick-up charger coil 480external to the wireless sensor package 250, 450 or 650 may be used toinductively charge the internal charging coil 482 coupled to the battery478 through rectifier 484. A motion charger and battery 366 c maycomprise a charging pick-up coil in close proximity to a permanentmagnet 488, wherein the permanent magnet moves in an axial directiondepending upon the axial motion of the wireless sensor package 250. Themagnet 488 has mass and travels back and forth between the springs 490when the wireless sensor package 250, 450 or 650 is moving up and down,thus charging the battery 478 through the diode 484. The battery 478 maybe replaced with the capacitor 492 and be similarly charged. It iscontemplated and within the scope of this disclosure that other sourcesof power 366 not disclosed herein may be also be utilized to power thecomponents of the wireless sensor package 250.

While embodiments of this disclosure have been depicted, described, andare defined by reference to example embodiments of the disclosure, suchreferences do not imply a limitation on the disclosure, and no suchlimitation is to be inferred. The subject matter disclosed is capable ofconsiderable modification, alteration, and equivalents in form andfunction, as will occur to those ordinarily skilled in the pertinent artand having the benefit of this disclosure. The depicted and describedembodiments of this disclosure are examples only, and are not exhaustiveof the scope of the disclosure.

1. A pump jack adapted for monitoring sucker rod load and position,comprising: a sucker rod string in a well bore pipe; a polished rodcoupled to the sucker rod string; a horsehead coupled to the polishedrod; a rocker beam coupled to the horsehead; a connecting rod coupled tothe rocker beam; a counter weight coupled to the connecting rod; apittman arm coupled to the connecting rod and counter weight; a variablespeed motor-gear drive assembly coupled to the pittman arm forrotational movement thereof; a frame pivotally coupled to the rockerbeam; a base attached to the frame; first and second force sensorsattached to a proximate end of the sucker rod string, wherein the firstand second force sensors measure elongation and compression stresses,respectively, of the sucker rod string while the sucker rod string movesup and down in the well bore pipe; a position sensor attached toward theproximate end of the sucker rod string, wherein the position sensordetermines positions of the sucker rod string; a sensor interfaceassembly having wireless transmitting capabilities, wherein the sensorinterface assembly is attached to the sucker rod string, and is coupledto the first and second force measurement sensors and the positionsensor, whereby the sucker rod string forces and position informationare wirelessly transmitted therefrom; and a wireless receiver coupled tothe variable speed motor-gear drive assembly, wherein the wirelessreceiver receives the force and position information transmitted fromthe interface assembly for determining control of rotational speed ofthe variable speed motor-gear drive assembly.
 2. The pump jack accordingto claim 1, wherein the position sensor is a tri-axial accelerometer. 3.The pump jack according to claim 1, wherein the position sensor is adistance measuring device for measuring distances between the proximateend of the sucker rod string and a reference point.
 4. The pump jackaccording to claim 3, wherein the distance measuring device usesultrasonic pulses for measuring the distances.
 5. The pump jackaccording to claim 3, wherein the distance measuring device uses radiofrequency pulses for measuring the distances.
 6. The pump jack accordingto claim 3, wherein the distance measuring device uses infrared pulsesfor measuring the distances.
 7. The pump jack according to claim 3,wherein the distance measuring device uses laser light pulses formeasuring the distances.
 8. The pump jack according to claim 1, furthercomprising a well bore pipe elongation distance sensor coupled to aproximate end of the well bore pipe, and from which elongation length ofthe well bore pipe is available as elongation data.
 9. The pump jackaccording to claim 1, further comprising pressure and flow rate sensorscoupled to a flange/fluid takeoff assembly that is coupled to theproximate end of the well bore pipe, and from which pressure and flowrate at the flange/fluid takeoff assembly are available as pressure andflow rate data, respectively.
 10. An apparatus for monitoring positionand load of a sucker rod in a pump jack, comprising: first and secondforce sensors attached at a proximate end of a sucker rod string of apump jack, wherein the first and second force sensors measure elongationand compression stresses, respectively, of the sucker rod string whilethe sucker rod string moves up and down in a well bore pipe; a positionsensor attached toward the proximate end the sucker rod string, whereinthe position sensor determines positions of the sucker rod string; and asensor interface assembly having wireless transmitting capabilities,wherein the sensor interface assembly is attached to the sucker rodstring, and is coupled to the first and second force measurement sensorsand the position sensor, whereby the sucker rod string forces andposition information are wirelessly transmitted therefrom.
 11. Theapparatus according to claim 10, wherein the position sensor is adistance measuring device for measuring distances between the proximateend of the sucker rod string and a reference point.
 12. The apparatusaccording to claim 11, wherein the distance measuring device usesultrasonic pulses for measuring the distances.
 13. The apparatusaccording to claim 11, wherein the distance measuring device uses radiofrequency pulses for measuring the distances.
 14. The apparatusaccording to claim 11, wherein the distance measuring device usesinfrared pulses for measuring the distances.
 15. The apparatus accordingto claim 11, wherein the distance measuring device uses laser lightpulses for measuring the distances.
 16. A pump jack adapted formonitoring sucker rod load and position, comprising: a sucker rod stringin a well bore pipe; a polished rod coupled to the sucker rod string; ahorsehead coupled to the polished rod; a rocker beam coupled to thehorsehead; a connecting rod coupled to the rocker beam; a counter weightcoupled to the connecting rod; a pittman arm coupled to the connectingrod and counter weight; a variable speed motor-gear drive assemblycoupled to the pittman arm for rotational movement thereof; a framepivotally coupled to the rocker beam; a base attached to the frame;first and second force sensors attached to a proximate end of the suckerrod string, wherein the first and second force sensors measureelongation and compression stresses, respectively, of the sucker rodstring while the sucker rod string moves up and down in the well borepipe; a sensor interface assembly having wireless transmittingcapabilities, wherein the sensor interface assembly is attached to thesucker rod string, and is coupled to the first and second forcemeasurement sensors, whereby the sucker rod string force information iswirelessly transmitted therefrom; a distance measuring device attachedon a plan of the base and under the sensor interface assembly, whereinthe position sensor determines positions of the sucker rod string bymeasuring distances between the distance measuring device and the sensorinterface assembly; and a wireless receiver coupled to the variablespeed motor-gear drive assembly, wherein the wireless receiver receivesthe force information transmitted from the sensor interface assembly,and wherein position information from the distance measuring device iscoupled to the variable speed motor-gear drive assembly, whereby controlof rotational speed of the variable speed motor-gear drive assembly isdetermined from the force and position information.
 17. The pump jackaccording to claim 16, wherein the distance measuring device usesultrasonic pulses for measuring the distances.
 18. The pump jackaccording to claim 16, wherein the distance measuring device uses radiofrequency pulses for measuring the distances.
 19. The pump jackaccording to claim 16, wherein the distance measuring device usesinfrared pulses for measuring the distances.
 20. The pump jack accordingto claim 16, wherein the distance measuring device uses laser lightpulses for measuring the distances.
 21. The pump jack according to claim16, further comprising a well bore pipe elongation distance sensorcoupled to a proximate end of the well bore pipe, and from whichelongation length of the well bore pipe is available as elongation data.22. The pump jack according to claim 16, further comprising pressure andflow rate sensors coupled to a flange/fluid takeoff assembly that iscoupled to the proximate end of the well bore pipe, and from whichpressure and flow rate at the flange/fluid takeoff assembly areavailable as pressure and flow rate data, respectively.
 23. An apparatusfor monitoring position and load of a sucker rod in a pump jack,comprising: first and second force sensors attached at a proximate endof a sucker rod string of a pump jack, wherein the first and secondforce sensors measure elongation and compression stresses, respectively,of the sucker rod string while the sucker rod string moves up and downin a well bore pipe; a sensor interface assembly having wirelesstransmitting capabilities, wherein the sensor interface assembly isattached to the sucker rod string, and is coupled to the first andsecond force measurement sensors, whereby the sucker rod string forceinformation is wirelessly transmitted therefrom; a distance measuringdevice attached on a plane of a base of the pump jack and under thesensor interface assembly, wherein the distance measuring devicedetermines positions of the sucker rod string by measuring distancesbetween the distance measuring device and the sensor interface assembly;and a wireless receiver coupled to the variable speed motor-gear driveassembly, wherein the wireless receiver receives the force informationtransmitted from the sensor interface assembly, and wherein positioninformation from the distance measuring device is coupled to thevariable speed motor-gear drive assembly, whereby control of rotationalspeed of the variable speed motor-gear drive assembly is determined fromthe force and position information.
 24. The apparatus according to claim23, wherein the distance measuring device uses ultrasonic pulses formeasuring the distances.
 25. The apparatus according to claim 23,wherein the distance measuring device uses radio frequency pulses formeasuring the distances.
 26. The apparatus according to claim 23,wherein the distance measuring device uses infrared pulses for measuringthe distances.
 27. The apparatus according to claim 23, wherein thedistance measuring device uses laser light pulses for measuring thedistances.